June 28, 2004 Is there a relationship between a cancer patient’s genetic makeup and quality of life?
A team of American and Canadian cancer researchers, led by Jeff Sloan, Ph.D., at Mayo Clinic in Rochester, Minn., think so. They’ve found preliminary evidence that suggests a cancer patient’s genetic makeup influences how the patient experiences fatigue, one of the most common side effects of cancer.
Dr. Sloan will report their findings during a plenary presentation at the 40th annual meeting of the American Society of Clinical Oncology (ASCO), June 7, in New Orleans. The study involved 494 cancer patients, and is believed to be the first finding of a possible link between genetics and a cancer patient’s quality of life.
"Genetic variants are now used to determine how cancer patients physically respond to treatment and the types of outcomes they will have," says Dr. Sloan. "We thought the possibility of linkages also existing between genetics and the way a cancer patient experiences quality of life was a plausible theory."
According to Dr. Sloan, "We know that cancer patients who have good quality of life and do not feel tired all the time or stressed out tend to cope better with the burden of having cancer.
"The ultimate goal would be to use information about a cancer patient’s genetic makeup to tailor individualized treatments for quality of life in the same manner as individualized treatments for the tumor itself," he says.
"Being able to identify cancer patients who have a predisposition to fatigue or other quality of life problems can mean earlier and better uses of resources so treatment and support services can be provided to help them have the best quality of life to cope with their disease."
The study was part of an international phase 3 clinical study, N9741, coordinated by the North Central Cancer Treatment Group (NCCTG) to test a new combination of chemotherapy drugs for treatment of colorectal cancer. All 494 patients in the study had previously been diagnosed with advanced colorectal cancer.
Before beginning chemotherapy, the patients donated their DNA through blood samples. They also completed questionnaires about their quality of life, which provided baseline information about their level of distress with having cancer.
The DNA samples allowed researchers to isolate three folate genes -- DPYD, MTHFR and TYMS -- that indicate the health of a person’s cells and risk for disease. The researchers found that patients with two variant forms of the DPYD gene were significantly less likely to say they were fatigued than patients who had the gene. The researchers also learned that patients who had a marker called TSER near the TYMS gene were more likely to report distress and fatigue than patients without the marker. (The researchers found no relationship between folate gene MTHFR and fatigue.)
"These findings indicate that a relationship between genetic makeup and how a cancer patient experiences fatigue seems to exist," says Dr. Sloan. "We arrived at these findings through a very cautious and skeptical approach because we realize this is novel research.
"At this point, we do not want to draw conclusions, but rather offer our findings to encourage more research for greater understanding and for helping patients have the best quality of life possible to most effectively cope with cancer," he says.
DISCLOSURE: The National Cancer Institute funded clinical study N9741 of which this study was a part. In addition to Dr. Sloan, the research team included Daniel Sargent, Ph.D., and X. Zhao, Ph.D., Mayo Clinic in Rochester, Minn.; Howard McLeod, Ph.D., Washington University School of Medicine in St. Louis; C. Fuchs, Ph.D., Dana Farber Cancer Institute in Boston; R. Ramanathan, Ph.D., University of Pittsburgh in Pittsburgh; S. Williamson, M.D., University of Kansas Medical Center in Kansas City; B. Findlay, M.D., National Cancer Institute of Canada in St. Catherine’s Ontario; R. Morton, M.D., Iowa Oncology Research Associates CCOP in Des Moines; R. Goldberg, M.D., The University of North Carolina at Chapel Hill.
The NCCTG is a network of more than 400 community-based cancer treatment clinics in the United States and Canada that work with Mayo Clinic to conduct clinical studies for advancing cancer treatment.
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